If reports are to be believed, dataminers have confirmed that the third evolution of the "Pokemon Sun and Moon" starters would be Sirene, Beltigre and Robinroot. The demo leaks have revealed the starter Pokemon final evolution. Dataminers have also confirmed that the Split evolution theories were nothing more than rumors.
Certain concept art was revealed online before the demo for "Pokemon Sun and Moon" was released. One turned out to be true while the other a rumor. It was previously thought that starters Rowlett, Litten and Popplio will have distinct "Pokemon Sun and Moon" evolution. Dataminers have supposedly proved this wrong and found no evidence of split evolution.
Game Freak had already showcased the second evolution forms of the "Pokemon Sun and Moon" starters early-October. Another leaked concept art showed final evolutions to be very similar to the second evolutions.
After the demo has been datamined, it has been proved that the concept art was true and these are final evolutions of the "Pokemon Sun and Moon" starters. One can watch the video here for evidence.
As per the dataminers, the Pokedex currently features about 800 Pokemon but not all of them are available in the "Pokemon Sun and Moon" demo. The "totem" Pokemon specifically cannot be viewed although that still leaves most of the roster visible to anyone with know-how.
As per Kotaku, certain aspects of "Pokemon X & Y" also got leaked including the map and mega evolutions. Some of the leaks happened under exact circumstances as the "Pokemon Sun and Moon" leaks. Game Freak released a demo for ORAS and dataminers were at it to leak various aspects of the game.
Thus, "Pokemon Sun and Moon" fans must turn off their Internet else all these leaks will spoil the very fun of the game. Stay tuned on GameNGuide for more updates on "Pokemon Sun and Moon."